Waterstone’s tips Brisingr as this Christmas's Harry Potter

Waterstone’s has predicted that a new fantasy children’s book will be “met with near Harry Potter-style demand” when it goes on sale on Saturday.

Brisingr, the third book in Christopher Paolini’s Inheritance Cycle, comes after more than 15 million copies have been sold of the first two books worldwide.

That number is dwarfed by sales of the Harry Potter series, which earlier this year passed the 400 million mark. But Toby Bourne, Waterstone’s fiction and children’s category manager, said Paolini’s books had such wide-ranging appeal that Brisingr had the potential to become the Christmas best-seller.

He said: “There are some fantastic novels out this Christmas for both children and adults, but Brisingr has the potential to outsell all of them.

'Like Rowling and Philip Pullman, Paolini’s books are great adventure stories but with a lot more going on in their pages than just non-stop action, and keep readers of all ages gripped.”

Paolini is an American author who published his first book in the series, Eragon, when he was only 19. It was picked up by Hollywood and turned into a film that grossed £137 million ($250 million). He is still just 24.

Claudia Mody, who buys children’s books for the bookseller, even forecast that Paolini’s series could follow a similar trajectory to JK Rowling’s.

She said: “It’s our biggest pre-order campaign for anything since the final Harry Potter novel. Bigger than Sebastian Faulk’s James Bond novel, Stephanie Meyer’s Twilight or Delia Smith’s How to Cheat at Cooking. It’s going to be huge.”

She added: “It wasn’t until Harry Potter and the Prisoner of Azkaban that people started counting down the days before the new JK Rowling book was out. It’s the same with Paolini – Brisingr is our most asked for book.”